The extent to which barometric fluctuations have acted as final causes in the production of earthquakes may be judged of by a comparison of the times of barometric variation and the times at which earthquakes have occurred. Three important laws of barometric variation are the following:— 1. In the world generally the average barometric pressure is highest in winter. (Exceptions occur near Iceland and in the North Pacific.) 2. The summer and winter monthly mean barometer differs least near the equator and over the great oceans. They differ most over the great continents and generally with increasing latitude. 3. The greatest number of barometrical fluctuations usually take place in winter. Inasmuch as there are generally more earthquakes in winter than in summer, the first of these laws would indicate that this might be due to the greater load which acts upon the crust of the earth at that season. The second law would indicate that the distinction between the winter and summer earthquakes ought to be most marked in high latitudes, which, if we refer to the table on p. 257, we observe to be borne out by the results of observation. The countries where there are as many earthquakes in winter as in summer are chiefly those in low latitudes. The number of these countries from which we have records are, however, few. Facts opposed to the idea that earthquakes may be caused by an increase of barometric pressure are the results of observations like those of Schmidt and Rossi, which show that earthquakes chiefly occur with a low barometer. Assuming that these latter observations will be found by future investigators to be generally true, we must conclude that the relief of atmospheric pressure has an influence upon the occurrence of earthquakes. Such a conclusion would partially accord with the third barometrical law, or the fact that there are more occasions on which we get a low barometer during the winter months. Other writers who have examined this question are Volger, Kluge, Andrès, and Poly. The latter investigator sought a connection between earthquakes and revolving storms, in the centres of which there is usually an abnormal decrease of atmospheric pressure. If an area over which such a sudden change in pressure took place was in a critical state, it is not difficult to see that storms such as Poly refers to might sometimes be accompanied by earthquakes.